Assembly methods for liquid metal battery with bimetallic electrode

Abstract

Electrochemical cells operating with molten electrodes and electrolyte, where the cathode is an alloy of a metal and metalloid, may be assembled in a discharged state by combining first an anodic metal with a cathodic metal to form a binary alloy. This binary alloy is then placed in a cell housing with the metalloid and the electrolyte, all in the solid state. The temperature is raised to, and maintained at, a temperature above the melting point of the highest melting component until components assembled into horizontal layers of electrolyte above a layer of a ternary alloy formed by the combination of the binary alloy and the metalloid. A charge and discharged cycle is then run through the electrochemical cell.

What is claimed is: 
     
       1. A method of assembling an electrochemical cell having a housing and positive and negative current collectors, the method comprising:
 providing a binary alloy formed from an anodic metal of group IA or IIA of the periodic table of the elements and a cathodic metal other than the anodic metal; 
 placing the binary alloy in a solid phase in the housing with a metalloid in a solid phase and an electrolyte in a solid phase, the electrolyte comprising a salt of the anodic metal; 
 heating the binary alloy, the metalloid and the electrolyte to form two liquid layers, wherein a first layer comprises the electrolyte, and a second layer comprises an alloy of the anodic metal, the cathodic metal and the metalloid; 
 contacting the negative current collector with the electrolyte and the positive current collector with the alloy; and 
 charging the electrochemical cell to drive the anodic metal in the alloy to the negative current collector. 
 
     
     
       2. The method of  claim 1 , wherein the anodic metal is an alkali metal. 
     
     
       3. The method of  claim 2 , wherein the alkali metal is sodium or lithium. 
     
     
       4. The method of  claim 1 , wherein the anodic metal is an alkaline earth metal. 
     
     
       5. The method of  claim 4 , wherein the alkaline earth metal is calcium or magnesium. 
     
     
       6. The method of  claim 1 , wherein the cathodic metal is selected from group IIIA, IVA or VA elements of the chemical periodic table. 
     
     
       7. The method of  claim 6 , wherein the cathodic metal is tin, lead or bismuth. 
     
     
       8. The method of  claim 1 , wherein the metalloid is selected from group IVA, VA or VIA elements of the chemical periodic table. 
     
     
       9. The method of  claim 8 , wherein the metalloid is antimony. 
     
     
       10. The method of  claim 1 , wherein the salt is a eutectic mixture of halide salts. 
     
     
       11. An electrochemical cell comprising:
 a positive current collector and a negative current collector electronically insulated from one another; 
 a binary alloy in a solid phase, the binary alloy comprising an anodic metal of group IA or IIA of the periodic table of the elements and a cathodic metal other than the anodic metal; 
 a metalloid in a solid phase; 
 an electrolyte in a solid phase, the electrolyte comprising a salt of the anodic metal; and 
 a housing, the housing containing the binary alloy, the metalloid, and the electrolyte, wherein the binary alloy, the metalloid and the electrolyte are configured such that when the electrochemical cell is heated to an operating temperature the anodic metal in a liquid phase has a density lighter than a density of the electrolyte in a liquid phase, and the electrolyte has a density lighter than a density of either of the cathodic metal and the metalloid in a liquid phase, and configured such that when the electrochemical cell is heated to an operating temperature the negative current collector contacts the anodic metal. 
 
     
     
       12. The electrochemical cell of  claim 11 , wherein the anodic metal is an alkali metal. 
     
     
       13. The electrochemical cell of  claim 12 , wherein the alkali metal is sodium or lithium. 
     
     
       14. The electrochemical cell of  claim 11 , wherein the anodic metal is an alkaline earth metal. 
     
     
       15. The electrochemical cell of  claim 14 , wherein the alkaline earth metal is calcium or magnesium. 
     
     
       16. The electrochemical cell of  claim 11 , wherein the cathodic metal is tin, lead or bismuth. 
     
     
       17. The electrochemical cell of  claim 11 , wherein the metalloid is antimony. 
     
     
       18. The electrochemical cell of  claim 11 , wherein the salt is a eutectic mixture of halide salts of the anodic salt. 
     
     
       19. The method of  claim 1 , wherein the cathodic metal and the metalloid are selected from group VA elements of the chemical periodic table. 
     
     
       20. The electrochemical cell of  claim 11 , wherein the cathodic metal and the metalloid are selected from group VA elements of the chemical periodic table.